ksmbd: prevent connection free while sending oplock brean notification

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

Author: namjaejeon

connection.c

@@ -485,6 +485,26 @@ void ksmbd_conn_init_server_callbacks(struct ksmbd_conn_ops *ops)
 	default_conn_ops.terminate_fn = ops->terminate_fn;
 }
 
+void ksmbd_conn_r_count_inc(struct ksmbd_conn *conn)
+{
+	atomic_inc(&conn->r_count);
+}
+
+void ksmbd_conn_r_count_dec(struct ksmbd_conn *conn)
+{
+	/*
+	 * Checking waitqueue to dropping pending requests on
+	 * disconnection. waitqueue_active is safe because it
+	 * uses atomic operation for condition.
+	 */
+	atomic_inc(&conn->refcnt);
+	if (!atomic_dec_return(&conn->r_count) && waitqueue_active(&conn->r_count_q))
+		wake_up(&conn->r_count_q);
+
+	if (atomic_dec_and_test(&conn->refcnt))
+		kfree(conn);
+}
+
 int ksmbd_conn_transport_init(void)
 {
 	int ret;

connection.h

@@ -168,6 +168,8 @@ int ksmbd_conn_transport_init(void);
 void ksmbd_conn_transport_destroy(void);
 void ksmbd_conn_lock(struct ksmbd_conn *conn);
 void ksmbd_conn_unlock(struct ksmbd_conn *conn);
+void ksmbd_conn_r_count_inc(struct ksmbd_conn *conn);
+void ksmbd_conn_r_count_dec(struct ksmbd_conn *conn);
 
 /*
  * WARNING

oplock.c

@@ -809,10 +809,12 @@ static int smb1_oplock_break_noti(struct oplock_info *opinfo)
 	work->conn = conn;
 
 	if (opinfo->op_state == OPLOCK_ACK_WAIT) {
+		ksmbd_conn_r_count_inc(conn);
 		INIT_WORK(&work->work, __smb1_oplock_break_noti);
 		ksmbd_queue_work(work);
 
 		wait_for_break_ack(opinfo);
+		ksmbd_conn_r_count_dec(conn);
 	} else {
 		__smb1_oplock_break_noti(&work->work);
 		if (opinfo->level == OPLOCK_READ)
@@ -925,10 +927,12 @@ static int smb2_oplock_break_noti(struct oplock_info *opinfo)
 	work->sess = opinfo->sess;
 
 	if (opinfo->op_state == OPLOCK_ACK_WAIT) {
+		ksmbd_conn_r_count_inc(conn);
 		INIT_WORK(&work->work, __smb2_oplock_break_noti);
 		ksmbd_queue_work(work);
 
 		wait_for_break_ack(opinfo);
+		ksmbd_conn_r_count_dec(conn);
 	} else {
 		__smb2_oplock_break_noti(&work->work);
 		if (opinfo->level == SMB2_OPLOCK_LEVEL_II)
@@ -1031,9 +1035,11 @@ static int smb2_lease_break_noti(struct oplock_info *opinfo)
 	work->sess = opinfo->sess;
 
 	if (opinfo->op_state == OPLOCK_ACK_WAIT) {
+		ksmbd_conn_r_count_inc(conn);
 		INIT_WORK(&work->work, __smb2_lease_break_noti);
 		ksmbd_queue_work(work);
 		wait_for_break_ack(opinfo);
+		ksmbd_conn_r_count_dec(conn);
 	} else {
 		__smb2_lease_break_noti(&work->work);
 		if (opinfo->o_lease->new_state == SMB2_LEASE_NONE_LE) {

server.c

@@ -270,17 +270,7 @@ static void handle_ksmbd_work(struct work_struct *wk)
 
 	ksmbd_conn_try_dequeue_request(work);
 	ksmbd_free_work_struct(work);
-	/*
-	 * Checking waitqueue to dropping pending requests on
-	 * disconnection. waitqueue_active is safe because it
-	 * uses atomic operation for condition.
-	 */
-	atomic_inc(&conn->refcnt);
-	if (!atomic_dec_return(&conn->r_count) && waitqueue_active(&conn->r_count_q))
-		wake_up(&conn->r_count_q);
-
-	if (atomic_dec_and_test(&conn->refcnt))
-		kfree(conn);
+	ksmbd_conn_r_count_dec(conn);
 }
 
 /**
@@ -310,7 +300,7 @@ static int queue_ksmbd_work(struct ksmbd_conn *conn)
 	conn->request_buf = NULL;
 
 	ksmbd_conn_enqueue_request(work);
-	atomic_inc(&conn->r_count);
+	ksmbd_conn_r_count_inc(conn);
 	/* update activity on connection */
 	conn->last_active = jiffies;
 	INIT_WORK(&work->work, handle_ksmbd_work);